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Overdrive snafu, moving to a conclusion

To: <healeys@autox.team.net>
Subject: Overdrive snafu, moving to a conclusion
From: "Simon Lachlan" <simon.lachlan@homecall.co.uk>
Date: Wed, 24 Jan 2007 16:19:22 -0000
I really have to thank you all for your help and advice in getting my
overdrive fixed and my car back on the road.

Special thanks for those who sent spreadsheets, articles and charts.
Feedback on/from those will either be forthcoming or should be elicited if
nothing materializes.

 

I could stop there and leave you all in suspense, but that would hardly be
sporting. You all remember the symptoms and how I havered around blaming the
throttle switch. You should know that I've had problems in this area before
and have done a devil of a lot of research and taken these devices apart
until I know the circuitry backwards. Hence the appeals on specifics such as
"what does a throttle switch do when it's failing?", by which I meant "what
falls apart?", not "what happens (elsewhere in the system[!]) when it
fails?". There is a subtle, but important, difference.

I took the dash switch off and tested it to my complete satisfaction. I did
the same with the relay and got current and continuity when and where I
should. I was less happy with the throttle switch, which tested OK, but
would never quite yield the magic "zero to one fifth throttle" adjustment
which the manual brags about. But, the ***** thing looked fine with no
apparent wear or slop in the bushes or curvature in the spring or wear on
the points etcetc.

After, seemingly, dozens of fiddles and tests and adjustments I've got it
working again. The throttle switch remains very trigger happy however and my
"one fifth" remains a chimera. I'm off on holiday tomorrow and won't be back
for 10 days or so. Anyhow, the weather is mostly foul and doesn't lend
itself to rewarding "test runs" down to the pub. So, I'll bide a while and
try again in a week or two.

What do I really think? The throttle switch is worn out and, with huge
patience and more luck than judgment, has been corralled into one last
effort. The relay isn't far behind and the interplay between these two forty
something year old performers is giving rise to the problems that I've been
experiencing. Replace the switch then the relay would probably do it. Note
"probably".

The advice to by pass the throttle switch is tempting, but it doesn't
resolve the question does it?  Being Irish, I could say that the by pass
answers a question, but is it the question that one should have asked in the
first place?

 

And thanks again for all your time and trouble,

Simon.




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